This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A128438 #32 Nov 24 2023 15:59:10
%S A128438 1,1,2,3,12,3,20,35,280,252,2520,2310,27720,25740,24024,45045,720720,
%T A128438 226893,4084080,775975,246341,235144,5173168,14872858,356948592,
%U A128438 343219800,2974571600,2868336900,80313433200,77636318760,2329089562800
%N A128438 a(n) = floor((denominator of H(n))/n), where H(n) = Sum_{k=1..n} 1/k, the n-th harmonic number.
%C A128438 This is very similar to A027611, which is a different sequence. - _N. J. A. Sloane_, Nov 21 2008
%C A128438 Indices where a(n) differs from A027611 are terms of A074791. - _Gary Detlefs_, Sep 03 2011
%H A128438 Amiram Eldar, <a href="/A128438/b128438.txt">Table of n, a(n) for n = 1..2310</a>
%e A128438 The sequence denominator(H(n))/n begins 1, 1, 2, 3, 12, 10/3, 20, 35, 280, 252, 2520, 2310, ..., so the present sequence begins 1, 1, 2, 3, 12, 3, 20, 35, 280, 252, 2520, 2310, ...
%p A128438 H:=n->sum(1/k,k=1..n): a:=n->floor(denom(H(n))/n): seq(a(n),n=1..34); # _Emeric Deutsch_, Mar 25 2007
%t A128438 seq = {}; s = 0; Do[s += 1/n; AppendTo[seq, Floor[Denominator[s]/n]], {n, 1, 30}]; seq (* _Amiram Eldar_, Sep 18 2021 *)
%t A128438 Table[Floor[Denominator[HarmonicNumber[n]]/n],{n,40}] (* _Harvey P. Dale_, Nov 24 2023 *)
%o A128438 (Python)
%o A128438 from sympy import harmonic
%o A128438 def A128438(n): return harmonic(n).q//n # _Chai Wah Wu_, Sep 27 2021
%Y A128438 Cf. A128437, A002805, A027611, A074791.
%K A128438 nonn
%O A128438 1,3
%A A128438 _Leroy Quet_, Mar 03 2007
%E A128438 More terms from _Emeric Deutsch_, Mar 25 2007